US5832729A - Hydraulic control system - Google Patents

Hydraulic control system Download PDF

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Publication number
US5832729A
US5832729A US08/571,270 US57127095A US5832729A US 5832729 A US5832729 A US 5832729A US 57127095 A US57127095 A US 57127095A US 5832729 A US5832729 A US 5832729A
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Prior art keywords
valves
control
source
valve
tandem
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Expired - Fee Related
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US08/571,270
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English (en)
Inventor
Brian John Reid
Isidoro Livraghi
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Aeroquip Vickers Ltd
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Trinova Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/30—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom
    • E02F3/32—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom working downwardly and towards the machine, e.g. with backhoes
    • E02F3/325—Backhoes of the miniature type
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3122—Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
    • F15B2211/3127—Floating position connecting the working ports and the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/455—Control of flow in the feed line, i.e. meter-in control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/57—Control of a differential pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups

Definitions

  • This invention relates to hydraulic control systems for use with apparatus capable of operating several functions simultaneously.
  • the invention has particular, but not exclusive, application to mobile machines, such as earth moving machines, in connection with which it will, in the main, be discussed for convenience.
  • earth moving machines such as excavators
  • three fixed displacement gear pumps and have function movements provided by linear and/or rotary hydraulic actuators.
  • the invention will now be discussed in relation to a mini excavator,
  • Mini excavators are normally provided with a hydraulic control circuit or system comprising three fixed-displacement gear pullups driven by a prime mover, and one or two hydraulic control valve blocks which admit respective pump flows at three distinct points in the control circuit.
  • control arrangements suffer from the disadvantage of achieving poor control of the machine functions, particularly:
  • Modified control circuits are known which address different aspects of this overall disadvantage but even if such modifications were to be brought together, they would not result in a control circuit or system which would achieve simultaneous operation of a plurality of functions without interaction or which would increase significantly the operational speed to reduce the overall machine cycle time.
  • a fluid power control apparatus comprising:
  • a first control section including first and second control valves connectable in tandem; and first and second sources of working fluid under pressure
  • the first source being operatively connectable to the higher priority control valve of the pair and the second source being operatively connectable to the interconnection between the valves, whereby on switching of the first valve from a neutral position the relationship between the said valves progressively alters from a tandem relationship to one in which the said valves are supplied separately by the respective sources.
  • the first control section includes a third control valve operatively connectable in tandem with the second control valve, the second source being operatively connectable to the interconnection between the second and third control valves.
  • a second control section having fourth and fifth control valves connectable in tandem and a third source of working fluid under pressure, the third source being operatively connectable to the higher priority valve of the fourth and fifth control valves, and the second source being operatively connectable to the interconnection between the fourth and fifth valves, whereby on switching of the fourth valve from a neutral position the relationship between the fourth and fifth valves progressively alters from a tandem relationship to one in which the fourth and fifth valves are supplied separately by the third and second sources respectively.
  • a sixth control valve connectable in tandem with the fifth control valve and/or in tandem with the third control valve, one port of the sixth control valve optionally being operatively connectable to a single acting actuator, and a further port thereof being operatively connectable to provide a boost fluid supply to a further actuator supplied by one or more of the other control valves.
  • a further interconnection between the third and fifth control valves, the second source being operatively connectable to the said interconnection whereby to supply working fluid to said third and fifth control valves.
  • the interconnection between the second source and the third and fifth control valves is pressure compensated, whereby to bias flow towards that of the third and fifth valves operating at lower pressure than the other.
  • the apparatus may optionally include a third control section including at least one control valve, operatively connected in the path between the second source and the first source.
  • the third control section may optionally include two control valves operatively connected in parallel.
  • the invention is also considered to reside in a control valve connected to a double acting actuator in a regenerative manner, wherein the reduced-area side of the actuator piston is connectable to tank during movement of the actuator in one direction, whereby to permit application of the pressure in the control valve over substantially the entire working surface area of one side of the actuator piston during movement of the actuator in the said direction.
  • the control valve may include a bleed orifice for selectively connecting the reduced-area side of the said piston to tank.
  • a vehicle including a control apparatus and/or a control valve as defined hereinabove.
  • the vehicle is configured as a mini-excavator.
  • a method of controlling a plurality of double acting actuators comprising:
  • the method may optionally include one or more of the following steps.
  • the invention is also considered to reside in a method of controlling a double acting actuator operatively connected in a regenerative relationship with a control valve and a source of working fluid under pressure, comprising the steps of:
  • Embodiments of the present invention thus include a hydraulic control system for a machine having a plurality of functions, the system comprising at least two independent control sections, each having an inlet followed by one or more control functions, and an outlet connectable to tank.
  • the independent control sections are grouped together to combine inlets and/or outlets without disturbing the characteristic of independence.
  • Tandem circuits may be employed in one or more of the control sections to provide a priority of pump flow to the first function of the or each section.
  • control sections may be interconnected.
  • a balancing connection may also be made, for example, between the two track sections, and/or a connection in parallel with, for example, the bucket function.
  • the balancing connection may include a pressure compensated balancing valve.
  • FIG. 1 is a diagrammatic view of a mini excavator
  • FIG. 2 is a typical hydraulic control circuit for the mini excavator of FIG. 1;
  • FIG. 3 is a known improved hydraulic control circuit for the mini excavator of FIG. 1;
  • FIG. 4 is a hydraulic control circuit in accordance with the present invention for the mini excavator of FIG. 1.
  • Mini excavator machines are generally constructed as shown in FIG. 1 and provided with a hydraulic control circuit as shown in FIG. 2.
  • the hydraulic circuit comprises a set of three fixed displacement gear pumps P1,P2,P3 driven by a prime mover 1, and one or two hydraulic control valve blocks which together admit the pump flows at three distinct points on the circuit P1',P2',P3'.
  • the valve blocks control the direction of the oil flow into linear hydraulic actuators (not shown) controlling a first arm 2 (boom), a second digging arm 3 (dipper), a bucket function 4 mounted and pivoted on the end of the dipper 3, a swing function 5 used to rotate the boom arm about a fixed vertical pivot mounted on the machine super structure and a dozer function 6 mounted at the front of the machine.
  • the valve blocks also control several rotary actuators (not shown) which in turn control two track drive motors 7 and a further swing function 8 achieved with a motor rigidly connected to the machine superstructure rotating against a slew ring fixed to the undercarriage of the machine and arranged to rotate the superstructure of the machine relative to its undercarriage.
  • An auxiliary service 9 is also provided to control a single acting function such as the hammer function shown, or a number of alternative options.
  • This standard circuit of FIG. 1 achieves a poor control of the machine functions, particularly, as already mentioned:
  • the standard circuit layout of FIG. 2 has the first pump flow P1' connected to one end of a combined valve and in a neutral valve state. This flow passes through the dipper 3 and RH track 7R sections and flows to tank T at the hammer section 9.
  • the second pump flow P2' is connected to the opposite end of the combined valve and this flow passes through the boom 2, bucket 4 and RH track 7R sections and then to tank T through the hammer section 9,
  • the third pump flow P3' is connected to a second valve after passing through a pilot supply valve L and then passes through the blade 6 and swing 5 sections before returning to tank T.
  • FIG. 3 shows an embodiment of this principle where the hammer section 9 uses one port connection 9a only to operate the hammer function.
  • the other port 9b is then connected externally through a check valve 11 to the boom cylinder (not shown).
  • a check valve 11 to the boom cylinder (not shown).
  • the standard circuit is constructed having each function within each of the three valve banks, connected in parallel, e.g. boom and bucket functions 2,4 as shown in FIG. 3.
  • Tandem circuits provide a priority of pump flow to the first section in the tandem group and thus prevents interaction between the functions in the group. Tandem circuits are normally employed when functions are required to be moved sequentially. The main disadvantage is that the circuit will not allow the two functions to be operated simultaneously, and, at all times, the first function takes priority over the following ones.
  • closed centre valves as a result of which it is possible to introduce individual function compensators to balance the distribution of flow between sections operating at different load pressure valve.
  • closed centre valves used with either fixed or variable displacement pumps are more complex and expensive than equivalent open centre valves currently in use.
  • a hydraulic control valve system or circuit in accordance with the present invention achieves both direction, flow and pressure control of a number of actuators both linear differential area and rotary types configured to control the functions of a machine.
  • Typical of this application is the mini-excavator of FIG. 1.
  • a valve circuit in accordance with the invention is shown in FIG. 4 and is arranged in three independent sections, S1,S2,S3 each with an inlet followed by several implement controls, and an outlet means of passing the flow to tank T.
  • Such a valve can be grouped together to combine inlets or outlets to achieve a more compact solution, yet remaining as three independent circuits.
  • a typical arrangement of the function controls on a mini-excavator are as shown in FIG. 4.
  • Valve section S1 controls or partially controls Dipper 3/ RH Track 7R/ and Auxiliary Function, e.g. hammer 9.
  • Valve section S2 controls or partially controls boom 2/ bucket 4/ LH track 7L and eg. hammer 9.
  • Valve section S3 controls or partially controls blade 8 and swing 6/ bucket 4/ LH track 7L/ RH track 7R.
  • valve section This layout allows one function in each valve section to be connected to a dedicated pump and therefore eliminate service interaction.
  • the remaining sections are normally connected in parallel and interaction within the valve section is possible.
  • valve sections are further modified as shown in FIG. 4 by the introduction of tandem circuits between:
  • Tandem circuits provide a priority of pump flow to the first function in each valve section and in sections where three functions are connected in tandem the priority is a cascade. If the first function is not selected, then priority passes to the second spool and so on to the third spool.
  • the control circuit also includes some interconnection between valve sections to achieve a better distribution of circuit flow to match the application requirements. This is achieved without, however, disturbing the priority order established for each pump.
  • One interconnection is a connection 13 from the outlet of valve section S3 to the valve section S2 at a position 14 between the boom and bucket sections 2,4.
  • a further improvement is the introduction of a balancing line 15 between the two track sections 7R,7L and a connection 16 in parallel with the bucket function 4 from the valve section S3.
  • valve section S3 Flow from valve section S3 is admitted to each line across a check valve 16a.
  • the balancing line 15 also includes a pressure compensated balancing valve 16b which ensures that flow entering the valve at B1 can be distributed evenly between ports B2 and B3.
  • the balancing valve 16b also permits the passage of flow from B2 to B3, and vice versa.
  • a regenerative circuit is further improved in accordance with the invention by the introduction of a bleed orifice 12 from the rod end to tank.
  • This orifice 12 allows a stalled or near-stalled actuator to develop its full load potential by applying its full pressure drop over the cylinder piston area rather than only the rod area during the full speed regenerative action.
  • FIG. 4 shows this feature applied to the dipper function 3 and the regenerating flow allows a dramatic increase in the actuator speed in its extending direction.
  • a further benefit of the regenerative function feature is its ability to eliminate cavitation on the piston side when the actuator is moved under a gravitational load.
  • the circuit also includes a summation flow line 17 from the auxiliary function 9 to the boom raise line across a check valve 18 as also shown in FIG. 4. This is included in the circuit to obtain the benefits as described earlier.
  • the two tracks 7L,7R are interconnected and this allows both tracks to be supplied from the same pump.
  • the present invention provides a circuit which greatly enhances the performance of the functions by an efficient distribution of flow.
  • the major benefits are increased function speed, simultaneous operation without load interaction for three functions, and under partially selected conditions the possibility to control more functions simultaneously.
  • the latter performance could only be achieved using either a more complex and expensive closed centre valve solution, or an open centre valve with a highly skilled operator.
  • This system achieves a high degree of performance at relatively low cost and requires only basic operator skills to achieve good performance.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Operation Control Of Excavators (AREA)
  • Fluid-Pressure Circuits (AREA)
US08/571,270 1994-12-14 1995-12-12 Hydraulic control system Expired - Fee Related US5832729A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9425273.1A GB9425273D0 (en) 1994-12-14 1994-12-14 Hydraulic control system
GB9425273 1994-12-14

Publications (1)

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US5832729A true US5832729A (en) 1998-11-10

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US (1) US5832729A (ko)
EP (1) EP0717198B1 (ko)
JP (1) JPH08240206A (ko)
KR (1) KR100248186B1 (ko)
CN (2) CN1080840C (ko)
DE (1) DE69530827T2 (ko)
GB (1) GB9425273D0 (ko)

Cited By (11)

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US6195989B1 (en) * 1999-05-04 2001-03-06 Caterpillar Inc. Power control system for a machine
US6330797B1 (en) * 1996-09-19 2001-12-18 Yanmar Diesel Engine Co., Ltd. Hydraulic circuit for turning excavator
US6357231B1 (en) 2000-05-09 2002-03-19 Clark Equipment Company Hydraulic pump circuit for mini excavators
US6742619B2 (en) 2001-10-03 2004-06-01 Trelleborg Ab Engine mounts, such as for a skid steer loader, having internally snubbed shocks and vibration isolators, and a method of making the engine mounts
US20050138850A1 (en) * 2003-12-15 2005-06-30 Brickner Chad T. Method of modulating a boom assembly to perform in a linear manner
US20050210871A1 (en) * 2004-03-27 2005-09-29 Cnh America Llc Work vehicle hydraulic system
US20060021338A1 (en) * 2004-07-30 2006-02-02 Deere & Company, A Delaware Corporation Increasing hydraulic flow to tractor attachments
US20080078174A1 (en) * 2006-09-29 2008-04-03 Kubota Corporation Backhoe Hydraulic System
US20090137944A1 (en) * 2007-11-27 2009-05-28 Brett Haarala Medical system and catheter connector apparatus
US20120330516A1 (en) * 2011-06-21 2012-12-27 Hiroshi Horii Operating machine
US9211832B1 (en) * 2012-05-16 2015-12-15 S.A.S. Of Luxemburg, Ltd. Salvage hold down attachment for excavators

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US6018895A (en) * 1996-03-28 2000-02-01 Clark Equipment Company Valve stack in a mini-excavator directing fluid under pressure from multiple pumps to actuable elements
SE525355C2 (sv) * 2003-06-19 2005-02-08 Hydrauto Valves Ab Stödbensventil
JP4825765B2 (ja) * 2007-09-25 2011-11-30 株式会社クボタ バックホーの油圧システム
WO2014160422A1 (en) * 2013-03-13 2014-10-02 Holaira, Inc. Fluid delivery system and method for treatment
JP6307292B2 (ja) * 2014-01-31 2018-04-04 Ｋｙｂ株式会社 作業機の制御システム
JP6005088B2 (ja) * 2014-03-17 2016-10-12 日立建機株式会社 建設機械の油圧駆動装置
WO2020196888A1 (ja) * 2019-03-28 2020-10-01 住友建機株式会社 ショベル及び施工システム
CN111218960A (zh) * 2020-04-09 2020-06-02 宜宾钢猫科技有限公司 水泥库底清理机器人及清理方法

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US3922855A (en) * 1971-12-13 1975-12-02 Caterpillar Tractor Co Hydraulic circuitry for an excavator
US5052179A (en) * 1989-07-07 1991-10-01 Kabushiki Kaisha Kobe Seiko Sho Pump discharge flow rate controlled by pilot pressure acting on vehicle drive valves

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US4210061A (en) * 1976-12-02 1980-07-01 Caterpillar Tractor Co. Three-circuit fluid system having controlled fluid combining
US4112821A (en) * 1976-12-03 1978-09-12 Caterpillar Tractor Co. Fluid control system for multiple circuited work elements
JPH0751796B2 (ja) * 1989-04-18 1995-06-05 株式会社クボタ バックホウの油圧回路
JP3139769B2 (ja) * 1992-12-04 2001-03-05 日立建機株式会社 油圧再生装置

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Publication number Priority date Publication date Assignee Title
US3922855A (en) * 1971-12-13 1975-12-02 Caterpillar Tractor Co Hydraulic circuitry for an excavator
US5052179A (en) * 1989-07-07 1991-10-01 Kabushiki Kaisha Kobe Seiko Sho Pump discharge flow rate controlled by pilot pressure acting on vehicle drive valves

Cited By (16)

* Cited by examiner, † Cited by third party
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US6330797B1 (en) * 1996-09-19 2001-12-18 Yanmar Diesel Engine Co., Ltd. Hydraulic circuit for turning excavator
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Publication number Publication date
CN2252264Y (zh) 1997-04-16
DE69530827D1 (de) 2003-06-26
EP0717198A3 (en) 1998-01-14
JPH08240206A (ja) 1996-09-17
CN1080840C (zh) 2002-03-13
EP0717198B1 (en) 2003-05-21
DE69530827T2 (de) 2004-04-08
KR100248186B1 (ko) 2000-04-01
EP0717198A2 (en) 1996-06-19
KR960023846A (ko) 1996-07-20
CN1132320A (zh) 1996-10-02
GB9425273D0 (en) 1995-02-08

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